This invention relates generally to automobile air conditioning systems and specifically to systems for controlling the inside temperature of an automobile to maintain the inside temperature in a comfortable range or to protect the contents of the automobile from becoming overheated on excessively hot days or to prevent freezing on cold days.
Automobile operators and passengers in warmer climates and on unusually hot summer days in most climates experience considerable discomfort when they enter an automobile which has been parked in the hot sun or in an uncooled garage during hot weather. Air conditioning technology for automobiles during operation is a well-developed art, and automobile air conditioners are very common. The most common automobile air conditioners are driven directly from the automobile engine by means of a belt and pulley or some other mechanical linkage. Some automobile air conditioners are driven by an electric motor, such as described in U.S. Pat. Nos. 2,970,456, and 4,038,835. The prior art electrically driven units are not suitable for prolonged use except when the automobile engine is running because of the high energy consumption of such units.
Automobile air conditioners of the conventional type may be described as "brute force" systems, because little or no effort is made to prevent heat transfer in or out of the automobile, the emphasis being on large and powerful air conditioning units.
Various efforts have been made to use solar energy, e.g. as described in U.S. Pat. Nos. 4,307,575, 3,943,726, 4,658,597, and 4,658,599, but such units have not gained general acceptance.
There are many types of sunshades, reflection devices, etc., to control or prevent the sun from shining through a window, or to provide for entry of light with some degree of thermal insulation. Examples of this class of devices are described in the following U.S. Pat. Nos. Des. 296,430, 1,444,735, 1,648,994, 2,111,350, 2,267,542, 2,382,566, 2,514,316, 2,546,438, 2,547,632, 2,619,168, 2,717,036, 2,745,150, 2,874,612, and 3,126,052.
Temperature control devices for automobile and aircraft compartments, etc., are in common use. One such device is described in U.S. Pat. No. 4,497,240.
Brock, U.S. Pat. No. 3,680,467, discloses an air conditioner powered by compressed air which could operate for a period independently of the automobile engine, and which includes a retractable shade over the windshield and tinted windows to reduce solar heat in the car.
It is common practice in warmer climates to leave a small opening at the top of the windows to permit some circulation of air and the escape of heated air from an automobile parked in a hot location. This practice is of little value and introduces some security risk as it is possible to open most automobile doors with a wire if access can be gained through a window.